Guide for rock-drills



UNITED STATES PATENT CEEICE.

THOMAS MURDOCH, CF MIDDLETOVN, CONNECTICUT.

GUIDE FOR EOCK-DRILLS.

SPECIFICATION forming part of Letters Patent No. 364,278, dated .lune 7, 1887.

Application filed March 2.8, 1887. Serial No. 232,611. (No model.)

To all whom may concern,.-

Beit known that I, THOMAS MURDooH, of Middletown, in the county of Middlesex and State of Connecticut, have invented certain new and useful 4Improvements in Guides for Rock-Drills, of which the following is a full, clear, and exact description, whereby any one skilled in the art can make and use the saine.

My invention relates to the class of devices that are used for reaming out holes that have been drilled in rock for blasting purposes; and its object is Vto provide a device by means of which the accuracy of the reaming may be insured.

ln making a eut for rock-blasting a number of round holes are drilled in a straight line at convenient intervals, these holes being all in a common plane that conforms to the plane on which it is desired to separate the rock by blasting. After the round holes are drilled a certain direction is given to the cut by making V-shaped grooves along the sides of the holes. In order that these grooves shall be'inade true as to line and in this plane above referred to, a guide-plate is used that has in. it a mortise adapted to hold the square shank of the reamer while the grooves are being cut. In the device of this class most nearly resembling my present improvement the guide is held in place by screw-pins, and the reamer is held against the bottom ofthe mortise in the guide-plate by one man, the guideplate by another, while usually two men handle hammers for driving the reamer.

By the use of my improved device the work of al1 themen, except those using the hammers, is avoided in reaming, and this saving of labor and the fact that more absolute accuracy in reaming is insured than with prior devices form the main advantages of my improvenient.

My improvement consists in a guide-plate having a tubular projection on the lower side adapted to iit the drill-hole, with a square mortise-opening through one edge of the guideplate and one side of thetube, in combination with a locking device for the reamer; and it further consists in the said guide-plate with tubular extension and lateral mortise, in combination with the reamer-locking device, a

ldenotes a reamer, which is of usual material,

and is square 01 of an equivalent polygonal shape in cross-section, and has a groove-rornr ing point, a. The square shape of the shank or body of the reamer is preferred'as being Y that form in which the merchantable iron or steel for making the reamers may be readily procured in the markets, and it presents the proper form for holding in the mortise in the guide-plate to prevent it from rotating.

The letter b denotes the guide-plate, that is preferably of a dat piece of metal with a tubular extension on the under side and a lateral mortise, b', opening through one edge of the plate and one wall'of the extension and formed to correspond to the reamer in section, the latter being `adapted to fit and slide in this mortise. The pin c projects from the under side of the guideplate on one side of the tubular extension b, and on the other side is a leveling-screw, d, that ts in a threaded socket in the plate,with its end projecting below the plate.

The locking device e is composed of the slid ing bolt e', with its arms ez adapted to overlie the mortise and embrace the stud f, that is fast to or integral with the guide-plate and is preferably made of hardened steel. The bolt c is held on the plate, and in a measure guided in its sliding movement by the screw-bolt g, passing through the slot e and through the guide-plate or fast thereto. On the upper end of this screw-,bolt is arranged a clampiugnnt, that lnay be turned down upon the bolt and hold it irmly in place.

The operation of the device is as follows: The tubular extension on the lower part of the guide-plate, that is preferably tapered so as to insure its tit within the drill-hole, is inserted in the latter, and the pin c at the same time inserted in the guide-hole, and the leveling ICO screw d is then turned until its point rests upon the surface of the rook. The bolt has been slid back to the position indicated in dotted lines in Fig, 1 before the guide-plate has been placed, as described, with the body or shank of the reanier, that has been previously fitted into the drill-hole, lying in the mortise. The bolt is then slid forward and clamped in place, the arms of the bolt, ineonneetion with .the sides of the mortisein the guide-plate and the stud f, forming a fixed guide for the reamer.

I claim as my invention* 1. In combination with a reamer, a guideplate having a mortise into Whieh the polymonal-shaped shank of the reamer lits, and the looking device that holds the reamer in the mortise of the guide/plate, all substantially as described.

2. In combination with the guide-plate having the tubular extension and the 1nortiscopening through the edge of the plate and the -cla1npscrew and nut, and. the lug, all substantially as described.

I l THOMAS MURDOCH. Witnesses:

JN0. H SAGE,

JAMES GA STRONG. 

